Wire Grid Polarization Element with Germanium-Oxygen-Nitrogen Light-Absorbing Layer
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Solution Overview
Problem
Wire grid polarization elements face challenges in reducing reflectance for secondary linearly polarized light, leading to issues like temperature rise, scroll noise, and ghosting due to stray light, which existing light-absorbing layers with pure germanium cannot effectively address.
Innovation Solution
A light-absorbing layer with a germanium film containing oxygen and nitrogen is introduced on the opposite side of the substrate, with controlled refractive index and extinction coefficient values, reducing reflectance to 3.0% or lower by using a reactive sputtering method to adjust the oxygen and nitrogen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light-absorbing layer including pure germanium is provided on the wire grid, then the manufacturing process is simple, but the reflectance with respect to secondary linearly polarized light cannot be sufficiently reduced
Solution Approach 1:
The patent applies composite materials by combining germanium with oxygen and nitrogen to create a light-absorbing layer with optimized optical properties. This composite approach allows simultaneous achievement of low reflectance and manufacturing feasibility, resolving the contradiction between simple manufacturing and effective reflectance reduction.
Solution Approach 2:
The patent changes the chemical composition parameters of the germanium-based light-absorbing layer by incorporating oxygen and nitrogen. This parameter modification optimizes the refractive index and extinction coefficient to achieve reflectance of 3.0% or lower, while maintaining compatibility with existing manufacturing processes.
2Object-affected harmful factors
If the refractive index and extinction coefficient are optimized to reduce reflectance, then the reflectance decreases to 3.0% or lower, but the manufacturing process complexity increases
Solution Approach 1:
The patent optimizes specific material parameters (refractive index n and extinction coefficient k) of the germanium-based light-absorbing layer to achieve reflectance of 3.0% or lower. By carefully controlling the composition ratios of germanium, oxygen, and nitrogen, the patent achieves optimal optical properties without requiring complex manufacturing processes.
Solution Approach 2:
The use of composite materials (germanium-oxygen-nitrogen system) provides a flexible platform for parameter optimization. The patent achieves the desired optical properties by adjusting the composition ratios within this composite system, maintaining manufacturing simplicity while achieving low reflectance.
3Device complexity
If reflected light is incident on the electrooptical device, then the device structure remains simple, but temperature rise and scroll noise occur reducing device reliability
Solution Approach 1:
The patent converts the harmful reflected light into a beneficial effect by using it to verify the effectiveness of the light-absorbing layer. The reflected light that would normally cause temperature rise and scroll noise is instead absorbed by the optimized germanium-based layer, transforming a harmful factor into a demonstration of the solution's effectiveness.
Solution Approach 2:
The germanium-based light-absorbing layer acts as an intermediary between the wire grid and the electrooptical device. It mediates the interaction by absorbing reflected light before it can reach the electrooptical device, preventing temperature rise and scroll noise while maintaining overall device structural simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces reflectance for linearly polarized light vibrating in the extending direction of wire-shaped metal layers, effectively suppressing light reflection and associated issues like temperature rise and scroll noise in electrooptical devices.
Implementation Method 1
a light-absorbing layer including a germanium film containing at least one of oxygen and nitrogen is provided on an side opposite to the substrate with respect to the plurality of wire-shaped metal layers
Implementation Method 2
the refractive index n and the extinction coefficient k satisfy the following appropriate conditions (n,k)=(5,1), (n,k)=(4,1), (n,k)=(3,1)
Implementation Method 3
a reactive sputtering method to adjust the oxygen and nitrogen content
Data Source
AI summary
A wire grid polarization element includes a wire grid including a plurality of wire-shaped metal layers arranged in parallel on one surface of a substrate, and a light-absorbing layer including a germanium film containing at least one of oxygen and nitrogen is provided on a side opposite to the substrate with respect to the plurality of wire-shaped metal layers. Such a germanium film can be formed by mixing an oxygen gas or a nitrogen gas into an argon gas in film formation by reactive sputtering. In this case, a flow rate of the oxygen gas or the nitrogen gas is made appropriate and thus, a complex refraction index of the germanium film is set to an appropriate value, and a reflectance with respect to linearly polarized light vibrating in an extending direction of the wire-shaped metal layers is set to 3.0% or lower.